国际英语新闻：Poland mourns presidential plane crash victims

"A week ago we received, all of us, our entire nation, the tragic news about the catastrophe and its victims, news that has not reached our minds and our hearts even until today -- because the size of this tragedy, the largest in post-war Poland, exceeds our ability to understand what happened," Tusk said.

The memorial was on the first of two days of ceremonies in mostly Roman Catholic Poland and was to be followed by a funeral Mass for the presidential couple at St. John's Cathedral at 6 p.m. local time (1600 GMT).

At the family's insistence, the funeral for the late president and his wife was expected to go ahead as planned on Sunday, despite drifting volcanic ash from Iceland that has shut Europe's airports and forced the cancellation of thousands of flights.

People attend a commemoration ceremony for late Polish President Lech Kaczynski and other plane crash victims held at the Pilsudski Square in Warsaw April 17, 2010. Hundreds of thousands of Poles gathered in Warsaw's main square Saturday to mourn the late President Lech Kaczynski, his wife Maria, and other victims killed in an April 10 plane crash.

The first Polish couple and many of the country's military and state elite were killed when their plane crashed near Smolensk, Russia, while trying to land in thick fog ahead.

The delegation had planned to attend a memorial marking the 70th anniversary of the massacre of thousands of Polish army officers by Russian security forces in 1940.

Earlier on Saturday, pedestrians and vehicles came to a standstill at 8:56 a.m. (0656 GMT) in Warsaw, the exact time a week ago when the presidential jet crashed in Russia and plunged Poland into a deep grief not seen since the death of Pope John Paul II five years ago.